Water heater circulating coil



Aug. 18, 1931. AJFRIEDMAN 1,819,550

WATER HEATER CIRCULATING COIL Filed March s, 192

Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE f ARTHUR ERIEDMAN, OE CLEVELAND,Y OHIO, AssIeNoR To VTHE CLEVELAND HEATER COMPANY, on CLEVELAND, oHro, A CORPORATION OE OHIO i WATER HEATER CracULATrNG OoIL Application led March s, 192s.

This invention relates to improvements Vin gas fired liquid heaters and in particular to the circulating coils for gas burning domestic water heaters.

It has for its object the provision of a water heater circulating coil that is inexpensive and easy to manufacture, and that is more durable than the ordinary type of circulating coils, f and that is protected against the destructive action of the condensation products of combustion of the gaseous fuels used in gas burning water heaters. Y My invention, 1n general, consists 1n the accompanied by the formation of copper sulphate at the point offailure of the coil. It is common knowledge that most commercial lgases particularly manufactured gas,

upon burning give off an oxide of sulphur,

` as well as water vapor.

The accepted theory of this phenomena is that the condensation of water vapor,

which takes place on the heater coils, causes the formation of sulphurous acid by combining with the vaporous sulphur compound given off by the burning gas.

As the weak sulphurous acid thus formed on the heater coils runs to the bottom of the coils, a certain amount of it is converted into sulphuric acid, by reason of coming in contact with what copper oxide may be present on the heater coils. r

The acids thus formed collect at the point of the coils where they enter the coil coupling. At this point, there is apt to be present considerable copper oxide, if it is a brazed joint. The oxide referred to is present as la result of the action of the gas Haine used in the brazing operation.

Serial No. 258,872.`

Furthermore, theV copper tubing at the braz'ed joint is somewhat weakened, due to the heat applied in brazing, which causes some oxidation as well as annealing, both of which are apt to leave this portion of the copper tubing in a condition in which it is more susceptibleto the corrosive action of sulphuric. action than the other portions of the tube. y

' Disregarding forY the moment, the type of joint between the tubing and the coupling, whether it be a brazed joint or a union coupling, it is apparent that a part of the aforementionedl liquids, condensed from the products of combustion of the gaseous fuel, come to rest at `the the coils.

At thisA junction point, which is in close proximity to the heater burner, the condenjunction of the coupling and sation products are further concentrated by direct action of the flame and evaporation of excess water in the acid solution, producing Vconcentrated sulphuric acid, which readily combines with the copper kof the heater coil.

It is upon this theory, which is supported by the presence of copper sulphate at'the junction .of the coupling and the tubing, after the heater has been in use for some time," that the common cause of failure of the copper coilsof water heaters is vaccounted for.

vThe formation of scale and liming of theinterior ofthe heater coils`accelerates their deterioration. Under these conditions, when in operation, the' heater coils kare kept Y' at much higher` degree of temperature,

of the venturi type.

The accompanying drawing shows a front elevation, partly in section, of a water heater constructed in accordance with,l and adapted for use in practicing my invention.

Referring to the drawing, the reference numeral Yl, indicates the heater casing or acket of a conventional gas fired domestic water heater. This casing provides a housing for the copper circulating coils 2 which are adapted to beput in communication with the storage vessel by means ofthe lower and upper union-connections 3 and 4, respectively.

Means for applying heat to the coil is provided for by the gas burner 5, which is mounted on an air and gas mixing tube 7,

The burner 5 is positionod below the coils in the lower portion of the heat-er jacket. A gas cock 8 is mounted at the inlet end of the mixing tube 7, and is adapted to be connectedto a source of gas supply.

Guard ringsvS), are secured in any suitable manner around the heater coils at a point adjacent the lower coupling. This may be accomplished by forming the rings to snugly fit the tubing and slipping them over the tubing before the coupling is attached. A split guard ring may be used, permitting its application to the coil after the coupling is in place. The guard rings may be made of any suitable material., and it is particularly desirable to make them from a material which is not readily affected by the harmful ingredients in the products of combustion from Jthe ordinary gaseous fuels.

In the present instance, the rings are made of pure iron, which material has been found to be suitable for this purpose. Other materials could be used and it might be advisable in some cases to make these rings from copper, brass, or a ceramic material. When made of a material, similar to the material used in the construction of the circulating coils, such as copper or brass, the effect of the Vrings would be to lengthen the life of the coils in proportion to the thickness of the guard ring. In this case it would be necessary for the rings to corrode rst before the tubes can be attacked, due to the acid settling to the lowermost portion of the ring and combining with the material of the `ring before attacking the tubing.

It is apparent that my improved heater coil could be used in conjunction with oil burning water heaters as well as gas burning water heaters and that it could be used to advantage in the heating of liquids other than water, where said coils are subjected to treatment similar to that which they receive in gas iired water heaters.

Furthermore, it is to be understood that the particular forms of apparatus shown and described, and the particular procedure set forth, are presented. for purposes of eX- planation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as defined in the appended claims.

Having described my invention, I claim:

l. A gas fired water heater comprising, a heater casing, vertically arranged tubular circulating coils housed in said casing, a coupling member bonded to the lower ends of said coils so as to form an integral irremovable part thereof, means to apply heat to said coils, and means adjacent said coupling member carried by said coils to prevant the condensation products of combustion deposited on said coils from flowing to and collecting at the joint between said coupling member and said coils.

2. In a liquid heater, a circulating coil, ai

coupling member permanently braZed to the lower end of said coil so as to form an integral irremovable partthereof, and means adjacent to and spaced from said coupling member to prevent the collection of con-l densate at the joint between the coupling member and the coil. l

8. In a liquid heater, a circulating coil, a coupling member bonded to the lower end of said coil so as to form an integral irrei movable part thereof, and a ring of a material more resistant to thev action of an acid than the material of the coil encircling said coil at a point adjacent said coupling member to prevent the collection of condensate-v lo at the joint between said coil and coupling member. j

4. In a gasfired water heater, a vertically arranged tubular water circulating coil, a

coupling member bonded to the lower end* of said coil so as to form an integral irremovable part thereof, a gas burner for supplying heat to said circulating coil, and means comprising a guard ring made of a material relatively unaffected by the con! densation products of combustion as compared with the material of the coil encircling said coil at a point adjacent said coupling for the purpose of preventing corrosion vof the portion of said coil adjacent said coupling member.

5. The combination of a water heater circulating coil formed from a section of copper tubing, a coupling member brazed thereto, and an iron ring encircling and suplUO ported on said coil at a point adjacent its lower extremity and spaced from said coupling member for the purpose of preventing j of preventing the condensate deposited on said coil from collecting at the junction of said coil and coupling member.

In testimony whereof I aiix my signature.

ARTHUR FRIEDMAN. 

